Statically build QEMU

Downloads and builds QEMU 5.0.0. Uses the repo's toolchain's
clang, but the local ld for now.

To resolve issues finding the libraries on the CI servers.

Signed-off-by: Fuad Tabba <tabba@google.com>
Change-Id: I534b75ca9de950e7a06f363645790ab0eba654d1
diff --git a/Makefile b/Makefile
index 9b6507a..eaa09b9 100644
--- a/Makefile
+++ b/Makefile
@@ -211,13 +211,12 @@
 	cp $(BR_OUT)/images/rootfs.ext4 $@
 	cp $(BR_OUT)/per-package/host-qemu/host/share/qemu/efi-virtio.rom $@
 
-# The qemu binary and the libraries it requires
-prebuilts/linux-x86/qemu: buildroot
+# The qemu binary
+prebuilts/linux-x86/qemu:
 	- rm -rf $@
+	${SCRIPTS_DIR}/aarch64/build_qemu.sh $(OUT_DIR)/qemu ${TOOLCHAIN_CLANG}/bin
 	mkdir -p $@/bin
-	cp $(BR_OUT)/host/bin/qemu-system-aarch64 $@/bin
-	mkdir -p $@/lib
-	cp $(BR_OUT)/host/lib/lib* $@/lib
+	cp $(OUT_DIR)/qemu/qemu-system-aarch64 $@/bin
 
 
 ##